1. Field of the Invention
The present invention relates to a method for matching an upper protocol layer to a high speed serial bus, and more particularly, to a method for matching the upper protocol layer to the IEEE 1394 bus in order to effectively transfer data packets of an existing communications application to the IEEE 1394 bus, while maintaining transparency of the data packets.
2. Description of the Related Art
The IEEE 1394 bus which is a high speed serial bus allows real-time data transfer for a multimedia application. The IEEE 1394 bus provides an asynchronous service, an isochronous stream service, and an asynchronous stream service. In this specification, the isochronous stream service and the asynchronous stream service are collectively called a stream service.
FIG. 1 shows a communications layer for serving a general data communications application such as a file transfer protocol (FTP) and data flow when packets are transferred by the asynchronous service. Referring to FIG. 1, for example, data packets made by an existing communications application based on the TCP/IP of an asynchronous method such as the Internet do not specify a subaction type provided by the 1394 link. Therefore, the communications application of an upper layer is not effectively matched to the IEEE 1394 bus.
In order to match the communications application of the upper layer to the IEEE 1394 bus, it is possible to transfer data by the asynchronous service, considering that all the data packets sent by the upper layer correspond to asynchronous subaction or to transfer data by the isochronous stream service, considering that all the data packets correspond to isochronous subaction.
However, in the former case, it is difficult to effectively manage the 1394 serial bus resource. Namely, it is easy to load data provided by a connectionless oriented service such as the Internet protocol (IP) on the 1394 asynchronous packet. However, in a circumstance where few applications actively use the IEEE 1394 isochronous/asynchronous stream, the 1394 channel cannot be effectively utilized. Also, when asynchronous packets are congested in the circumstance where the isochronous service is commonly used, a basic cycle (125 ms) of the 1394 bus cannot be maintained. Accordingly, the isochronous service becomes unstable.
In the latter case, a limited channel source is wasted since channels are allocated to all connections or channels are allocated even when the amount of data is small. Accordingly, an overload may occur since channel capacity is exceeded.